NAME

Moose::Meta::TypeConstraint - The Moose Type Constraint metaclass

VERSION

version 2.2011

DESCRIPTION

This class represents a single type constraint. Moose's built-in type constraints, as well as constraints you define, are all stored in a Moose::Meta::TypeConstraint::Registry object as objects of this class.

A subroutine which returns a string suitable for inlining this type constraint. It will be called as a method on the type constraint object, and will receive a single additional parameter, a variable name to be tested (usually "$_" or "$_[0]".

This is optional.

inline_environment

A hash reference of variables to close over. The keys are variables names, and the values are references to the variables.

$constraint->equals($type_name_or_object)

Returns true if the supplied name or type object is the same as the current type.

$constraint->is_subtype_of($type_name_or_object)

Returns true if the supplied name or type object is a parent of the current type.

$constraint->is_a_type_of($type_name_or_object)

Returns true if the given type is the same as the current type, or is a parent of the current type. This is a shortcut for checking equals and is_subtype_of.

$constraint->coerce($value)

This will attempt to coerce the value to the type. If the type does not have any defined coercions this will throw an error.

If no coercion can produce a value matching $constraint, the original value is returned.

$constraint->assert_coerce($value)

This method behaves just like coerce, but if the result is not valid according to $constraint, an error is thrown.

$constraint->check($value)

Returns true if the given value passes the constraint for the type.

$constraint->validate($value)

This is similar to check. However, if the type is valid then the method returns an explicit undef. If the type is not valid, we call $self->get_message($value) internally to generate an error message.

$constraint->assert_valid($value)

Like check and validate, this method checks whether $value is valid under the constraint. If it is, it will return true. If it is not, an exception will be thrown with the results of $self->get_message($value).

$constraint->name

Returns the type's name, as provided to the constructor.

$constraint->parent

Returns the type's parent, as provided to the constructor, if any.

$constraint->has_parent

Returns true if the type has a parent type.

$constraint->parents

Returns all of the types parents as an list of type constraint objects.

$constraint->constraint

Returns the type's constraint, as provided to the constructor.

$constraint->get_message($value)

This generates a method for the given value. If the type does not have an explicit message, we generate a default message.

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